Question

If I fire a cannon straight up into the air, the cannon ball slows down as it rises to its apex, then speeds up as it falls. At any given distance from the ground, is the ball travelling at the same speed on the way DOWN
as it was on the way UP?Asked by: David A. Fechtor

Answer

The speed of the cannon ball is the same on its way both to and from the apex at every point between the ground and the apex, because the force of gravity decelerates it (as it approaches the apex) at the same rate as it accelerates it (as it departs from the apex).Answered by: Howie Soucek, BS Philosophy, Hampden-Sydney College, VA
Additional comment by Anton Skorucak, PhysLink.com Editor:

The above stated answer is not entirely correct in the case where one has to deal with drag or friction of the air. Namely,

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